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2023-01-05 LEARJET, INC.: Amendment 39-22299; Docket No. FAA-2022-0991; Project Identifier AD-2022-00155-T.
(a) EFFECTIVE DATE

    This airworthiness directive (AD) is effective March 9, 2023.

(b) AFFECTED ADS

    This AD affects AD 2001-03-05, Amendment 39-12109 (66 FR 10353, Febru-
    ary 15, 2001) (AD 2001-03-05).

(c) APPLICABILITY

    This  AD  applies to Learjet, Inc.,  Model 45  (Learjet 40),  Model 45
    (Learjet 45),  Model 45 (Learjet 70),  and  Model 45 (Learjet 75) air-
    planes,  certificated in any category,  with an original airworthiness
    certificate  or original export certificate of airworthiness issued on
    or before January 18, 2022.

(d) SUBJECT

    Air Transport Association (ATA) of America Code 36, Pneumatic.

(e) UNSAFE CONDITION

    This AD was prompted by  a determination that new or  more restrictive
    airworthiness limitations are necessary. The FAA is issuing this AD to
    address metal  fragments breaking  off the  anti-ice manifold assembly
    due to fatigue, which  could block a duct  in the anti-ice system  and
    result in an unannunciated loss of ice protection and subsequent  loss
    of control of the airplane.

(f) COMPLIANCE

    Comply with this AD within the compliance times specified,  unless al-
    ready done.

(g) MAINTENANCE OR INSPECTION PROGRAM REVISION

(1) For Learjet 40 and 45 variants:  Within 60 days  after  the  effective
    date of this AD, revise the existing inspection program by incorporat-
    ing the information in Learjet 40  Maintenance Manual  Temporary Revi-
    sion (TR) 04-33 or Learjet 45 Maintenance Manual TR 04-48,  both dated
    January 18, 2022, as applicable.  The initial compliance time  for the
    inspection is at the applicable time  specified in paragraph (g)(1)(i)
    or (ii) of this AD.

(i) For  airplanes  with more than 600 flight hours  since the most recent
    inspection of the anti-ice manifold assembly  was performed  as of the
    effective date of this AD:  Do the inspection  within 100 flight hours
    or 60 days  after the effective date  of  this  AD,  whichever  occurs
    first.

(ii) For airplanes with 600 flight hours or less since the most recent in-
     spection of the  anti-ice manifold assembly  was performed as  of the
     effective date of this AD: Do the inspection within 600 flight  hours
     after the most recent inspection or within 100 flight hours after the
     effective date of this AD, whichever occurs later.

(2) For Learjet 70 and 75 variants:  Within 60 days  after  the  effective
    date of this AD, revise the existing inspection program to incorporate
    the information identified in figure 1 to paragraph (g)(2) of this AD.
    The initial compliance time  for  the  inspection is at the applicable
    time specified in paragraph (g)(2)(i) or (ii) of this AD.

           FIGURE 1 TO PARAGRAPH (G)(2)  ANTI-ICE INSPECTION TASKS
    ______________________________________________________________________
    IRN
    NUMBER    TASK DESCRIPTION   TASK INTERVAL   MODEL/SERIAL EFFECTIVITY
    ______________________________________________________________________
    3010006     **Anti-ice        600 flight     Learjet 70/75: 45-0368,
                Manifold -        hours (T)      45-0446, 45-0456 through
                Perform                          45-2000, 45-2129, 45-2134
                Borescope                        through 45-4000
                Inspection
    ______________________________________________________________________

(i) For airplanes with more than 600 flight hours  since  the  most recent
    inspection of the anti-ice manifold  assembly was performed as of  the
    effective date of this AD:  Do the inspection within 100  flight hours
    or  60 days  after the  effective date  of this  AD, whichever  occurs
    first.

(ii) For airplanes with 600 flight hours or less since the most recent in-
     spection of the anti-ice manifold assembly  was  performed  as of the
     effective date of this AD:  Do the inspection within 600 flight hours
     after the most recent inspection or within 100 flight hours after the
     effective date of this AD, whichever occurs later.

(h) NO ALTERNATIVE ACTIONS OR INTERVALS

    After the existing inspection program has been revised as required  by
    paragraph (g) of this  AD, no alternative actions  (e.g., inspections)
    or  intervals,  may  be  used unless  the  actions  and  intervals are
    approved as an alternative  method of compliance (AMOC)  in accordance
    with the procedures specified in paragraph (k) of this AD.

(i) TERMINATING ACTION FOR PARAGRAPH (C) OF AD 2001-03-05

    Accomplishing the revision of the existing inspection program required
    by paragraph (g) of this  AD terminates the requirements of  paragraph
    (c) of AD 2001-03-05.

(j) SPECIAL FLIGHT PERMIT

    Special flight permits may be issued in accordance with 14 CFR  21.197
    and 21.199 to  operate the airplane  to a location  where the airplane
    can be inspected, provided the airplane is restricted from flying into
    known icing conditions.

(k) ALTERNATIVE METHODS OF COMPLIANCE (AMOCS)

(1) The  Manager,  Wichita ACO Branch,  FAA,  has the authority to approve
    AMOCs for this AD, if requested  using the procedures found in 14  CFR
    39.19. In  accordance with  14 CFR  39.19, send  your request  to your
    principal  inspector  or  responsible  Flight  Standards  Office,   as
    appropriate. If  sending information  directly to  the manager  of the
    certification  office,  send  it  to  the  attention  of  the   person
    identified in paragraph (l) of this AD.

(2) Before using any approved AMOC,  notify your appropriate principal in-
    spector, or lacking a principal inspector,  the manager of the respon-
    sible Flight Standards Office.

(l) RELATED INFORMATION

    For more information about this AD, contact Adam Hein, Aerospace Engi-
    neer,  Mechanical Systems  and  Propulsion Section,  FAA,  Wichita ACO
    Branch,  1801 S Airport Road, Wichita, KS 67209;  telephone (316) 946-
    4116; email: adam.hein@faa.gov.

(m) MATERIAL INCORPORATED BY REFERENCE

(1) The Director of the Federal Register  approved  the  incorporation  by
    reference  (IBR)  of the service information  listed in this paragraph
    under 5 U.S.C. 552(a) and 1 CFR part 51.

(2) You must use this service information as applicable  to do the actions
    required by this AD, unless the AD specifies otherwise.

(i) Learjet 40 Maintenance Manual Temporary Revision 04-33,  dated January
    18, 2022.

(ii) Learjet 45 Maintenance Manual Temporary Revision 04-48, dated January
     18, 2022.

(3) For service information identified in this AD,  contact Learjet, Inc.,
    One Learjet Way, Wichita, KS 67209-2942;  telephone 316-946-2000;  fax
    316-946-2220; email ac.ict@aero.bombardier.com; website bombardier.com

(4) You may view this service information at the FAA,  Airworthiness Prod-
    ucts Section,  Operational  Safety  Branch,  2200 South 216th St., Des
    Moines, WA.  For information  on the availability  of this material at
    the FAA, call 206-231-3195.

(5) You may view  this service information  that is incorporated by refer-
    ence at the National Archives and Records Administration  (NARA).  For
    information on the availability of this material at NARA-fr.inspection
    @nara.gov,   or   go   to:  www.archives.gov/federal-register/cfr/ibr-
    locations.html.

Issued on January 6, 2023.  Christina Underwood,  Acting Director, Compli-
ance & Airworthiness Division, Aircraft Certification Service.

FOR FURTHER INFORMATION CONTACT: Adam Hein, Aerospace Engineer, Mechanical
Systems and Propulsion Section,  FAA,  Wichita ACO Branch,  1801 S Airport
Road, Wichita, KS 67209;  telephone (316) 946-4116;  email: adam.hein@faa.
gov.
PREAMBLE 

DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2022-0991; Project Identifier AD-2022-00155-T;
Amendment 39-22299; AD 2023-01-05]
RIN 2120-AA64

Airworthiness Directives; Learjet, Inc., Airplanes

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Final rule.

-----------------------------------------------------------------------

SUMMARY: The FAA is adopting a new airworthiness directive (AD) for
certain Learjet, Inc., Model 45 airplanes. This AD was prompted by a
determination that new or more restrictive airworthiness limitations
are necessary. This AD requires revising the existing inspection
program to incorporate reduced inspection intervals for the anti-ice
manifold assembly. The FAA is issuing this AD to address the unsafe
condition on these products.

DATES: This AD is effective March 9, 2023.
The Director of the Federal Register approved the incorporation by
reference of certain publications listed in this AD as of March 9,
2023.

ADDRESSES:
AD Docket: You may examine the AD docket at regulations.gov under
Docket No. FAA-2022-0991; or in person at Docket Operations between 9
a.m. and 5 p.m., Monday through Friday, except Federal holidays. The AD
docket contains this final rule, any comments received, and other
information. The address for Docket Operations is U.S. Department of
Transportation, Docket Operations, M-30, West Building Ground Floor,
Room W12-140, 1200 New Jersey Avenue SE, Washington, DC 20590.
Material Incorporated by Reference:
For service information identified in this final rule,
contact Learjet, Inc., One Learjet Way, Wichita, KS 67209-2942;
telephone 316-946-2000; fax 316-946-2220; email
ac.ict@aero.bombardier.com; website bombardier.com.
You may view this service information at the FAA,
Airworthiness Products Section, Operational Safety Branch, 2200 South
216th St., Des Moines, WA. For information on the availability of this
material at the FAA, call 206-231-3195. It is also available at
regulations.gov under Docket No. FAA-2022-0991.

FOR FURTHER INFORMATION CONTACT: Adam Hein, Aerospace Engineer,
Mechanical Systems and Propulsion Section, FAA, Wichita ACO Branch,
1801 S Airport Road, Wichita, KS 67209; telephone (316) 946-4116;
email: adam.hein@faa.gov.

SUPPLEMENTARY INFORMATION:

Background

The FAA issued a notice of proposed rulemaking (NPRM) to amend 14
CFR part 39 by adding an AD that would apply to certain Learjet, Inc.,
Model 45 airplanes. The NPRM published in the Federal Register on
August 11, 2022 (87 FR 49556). The NPRM was prompted by a determination
that new or more restrictive airworthiness limitations are necessary.
In the NPRM, the FAA proposed to require revising the existing
inspection program to incorporate reduced inspection intervals for the
anti-ice manifold assembly.
The FAA issued a supplemental notice of proposed rulemaking (SNPRM)
to amend 14 CFR part 39 by adding an AD that would apply to certain
Learjet, Inc., Model 45 airplanes. The SNPRM published in the Federal
Register on November 10, 2022 (87 FR 67834). The SNPRM was prompted by
a determination that additional airplanes needed to be added to the
applicability. The SNPRM proposed to require revising the existing
inspection program to incorporate reduced inspection intervals for the
anti-ice manifold assembly and to add airplanes to the applicability.
The FAA is issuing this AD to address metal fragments breaking off the
anti-ice manifold assembly due to fatigue, which could block a duct in
the anti-ice system and result in an unannunciated loss of ice
protection and subsequent loss of control of the airplane.

Related Rulemaking

The FAA issued AD 2001-03-05, Amendment 39-12109 (66 FR 10353,
February 15, 2001) (AD 2001-03-05), for certain Learjet Model 45
airplanes. AD 2001-03-05 requires, among other actions, revising the
existing Learjet 45 maintenance program to incorporate additional
inspections and maintenance practices for the anti-ice manifold
assembly, including a 600-hour repetitive inspection interval of an
earlier design/part number of the anti-ice manifold. Since the FAA
issued AD 2001-03-05, the anti-ice manifold was redesigned, and the
inspection interval was extended to 1,200 flight hours. The design
approval holder subsequently determined that the design improvements
made to the anti-ice manifold assembly did not fully address the
original issue of vane cracking, so the 1,200-hour inspection on the
redesigned part is insufficient. However, the FAA determined that a
repetitive inspection interval of 600 flight hours is sufficient to
address the unsafe condition. Therefore, this AD requires revising the
existing inspection program to incorporate a reduced 600-hour
inspection interval for the redesigned part. Accomplishing the required
actions in this AD terminates the requirements of paragraph (c) of AD
2001-03-05.

Discussion of Final Airworthiness Directive


Comments

The FAA received comments from two individuals who supported the
SNPRM without change.

Conclusion

The FAA reviewed the relevant data, considered any comments
received, and determined that air safety requires adopting this AD as
proposed. Accordingly, the FAA is issuing this AD to address the unsafe
condition on these products. Except for minor editorial changes, this
AD is adopted as proposed in the SNPRM. None of the changes will
increase the economic burden on any operator.

Related Service Information Under 1 CFR Part 51

The FAA reviewed Learjet 40 Maintenance Manual Temporary Revision
(TR) 04-33 and Learjet 45 Maintenance Manual TR 04-48, both dated
January 18, 2022. This service information specifies reduced inspection
intervals for the anti-ice manifold assembly. These documents are
distinct since they apply to different airplane configurations. This
service information is reasonably available because the interested
parties have access to it through their normal course of business or by
the means identified in ADDRESSES.

Costs of Compliance

The FAA estimates that this AD affects 481 airplanes of U.S.
registry. The FAA estimates the following costs to comply with this AD:

Estimated Costs

Action
Labor cost
Parts cost
Cost per product
Cost on U.S. operators
Inspection program revision 1 work-hour x $85 per hour = $85
$0
$85
$40,885

Authority for This Rulemaking

Title 49 of the United States Code specifies the FAA's authority to
issue rules on aviation safety. Subtitle I, section 106, describes the
authority of the FAA Administrator. Subtitle VII: Aviation Programs,
describes in more detail the scope of the Agency's authority.
The FAA is issuing this rulemaking under the authority described in
Subtitle VII, Part A, Subpart III, Section 44701: General requirements.
Under that section, Congress charges the FAA with promoting safe flight
of civil aircraft in air commerce by prescribing regulations for
practices, methods, and procedures the Administrator finds necessary
for safety in air commerce. This regulation is within the scope of that
authority because it addresses an unsafe condition that is likely to
exist or develop on products identified in this rulemaking action.

Regulatory Findings

This AD will not have federalism implications under Executive Order
13132. This AD will not have a substantial direct effect on the States,
on the relationship between the national government and the States, or
on the distribution of power and responsibilities among the various
levels of government.
For the reasons discussed above, I certify that this AD:
(1) Is not a ``significant regulatory action'' under Executive
Order 12866,
(2) Will not affect intrastate aviation in Alaska, and
(3) Will not have a significant economic impact, positive or
negative, on a substantial number of small entities under the criteria
of the Regulatory Flexibility Act.

List of Subjects in 14 CFR Part 39

Air transportation, Aircraft, Aviation safety, Incorporation by
reference, Safety.

The Amendment

Accordingly, under the authority delegated to me by the
Administrator, the FAA amends 14 CFR part 39 as follows:

PART 39--AIRWORTHINESS DIRECTIVES

1. The authority citation for part 39 continues to read as follows:

Authority: 49 U.S.C. 106(g), 40113, 44701.

Sec. 39.13 [Amended]

2. The FAA amends Sec. 39.13 by adding the following new airworthiness
directive: